There is no single correct answer to this.
On the one hand, if unlinking the classloader is solving your permgen leakage problems, then you should continue to do that.
On the other hand, a "GC overhead limit exceeded" error means that your application is spending too much time garbage collection. In most circumstances, this means that your heap is too full. But that can mean one of two things:
The heap is too small for your application's requirements.
Your application has a memory leak.
You could assume that the problem is the former one and just increase the heap size. But if the real problem is the latter one, then increasing the heap size is just postponing the inevitable ... and the correct thing to do would be to find and fix the memory leak.
Don't call System.gc()
. It won't help.